An electrical apparatus is connected to a power supply and changes operation in accordance with variation of a power supply voltage of the power supply in accordance with drive of another electrical apparatus connected to the same power supply. The electrical apparatus includes a drive unit driven by the power supply, a voltage detection unit, a current detection unit, and a control unit which sets a threshold value with which a circuit breaker which breaks the power supply is not driven, based on (i) a power supply voltage of the power supply detected by the voltage detection unit when the drive unit is driven, (ii) a power supply voltage of the power supply detected by the voltage detection unit when the drive unit is not driven, and (iii) a current detected by the current detection unit when the drive unit is driven.

An electrical apparatus is connected to a power supply and changes operation in accordance with variation of a power supply voltage of the power supply in accordance with drive of another electrical apparatus connected to the same power supply. The electrical apparatus includes a drive unit driven by the power supply, a voltage detection unit, a current detection unit, and a control unit which sets a threshold value with which a circuit breaker which breaks the power supply is not driven, based on (i) a power supply voltage of the power supply detected by the voltage detection unit when the drive unit is driven, (ii) a power supply voltage of the power supply detected by the voltage detection unit when the drive unit is not driven, and (iii) a current detected by the current detection unit when the drive unit is driven.

According to an aspect of the present disclosure, a motor drive control device includes a motor drive unit having a plurality of switch elements connected to a power supply source and supplying a driving current to a plurality of phase coils of a motor, a control circuit unit outputting, to the motor drive unit, a drive control signal for operating the plurality of switch elements to sequentially switch energization patterns for the plurality of phase coils, and a current detecting circuit for detecting a voltage value corresponding to a magnitude of the driving current, wherein the control circuit unit includes a first determination unit determining whether a state of overcurrent where a magnitude of the driving current exceeds a predetermined overcurrent threshold occurs based on the voltage value each time an energization pattern is switched, and a second determination unit determining whether driving of the motor is in an abnormal condition based on a determination result of the first determination unit for a plurality of energization patterns.

The invention relates to a device and to a method for monitoring an electrical network in a rail vehicle. The electrical network includes at least one converter, at least one drive motor, at least one first phase line for electrical connection of the at least one converter and the at least one drive motor. A magnitude of a current change of a first phase current is determined. A network error in a partial network on the machine side is detected if at least one criterion based on the current change is met. The criterion based on a current change is met when the magnitude of the current change of the first phase current is greater than a predetermined current change threshold.

A hand-held electrically powered cut-off tool (100) for cutting concrete and stone by a rotatable cutting disc (105), the cut-off tool (100) comprising an electric motor (130) arranged to be controlled by a control unit (110) via a motor control interface (120), wherein the control unit (110) is arranged to obtain data indicative of an angular velocity of the cutting disc (105), and to detect a kickback condition based on a decrease in angular velocity, and wherein the control unit (110) is arranged to electromagnetically brake the electric motor (130) in response to detecting a kickback condition.

The invention relates to a device and to a method for monitoring an electrical network in a rail vehicle. The electrical network includes at least one converter, at least one drive motor, at least one first phase line for electrical connection of the at least one converter and the at least one drive motor. A magnitude of a current change of a first phase current is determined. A network error in a partial network on the machine side is detected if at least one criterion based on the current change is met. The criterion based on a current change is met when the magnitude of the current change of the first phase current is greater than a predetermined current change threshold.

A symptom of malfunction regarding operating characteristics of a switch should be detected exactly. A switch operating characteristic monitoring device is comprised of a current sensor that measures a close command current of a switch, an auxiliary switch that outputs signals from at least two or more auxiliary contacts with reference to positions of a contactor, a measurement unit that measures signals from the current sensor and the auxiliary switch, a diagnosis unit that judges whether or not a malfunction occurs, and a display unit that displays a malfunction when a malfunction has been determined. A threshold is obtained in advance from multiple results of an opening/closing test performed beforehand. A calculation is made for characteristic times which are obtained from the close command current and signals from the auxiliary switch during actual operation of a circuit breaker. If a deviation is found by comparison with a threshold, a malfunction is determined.

In a method for identifying a deflection or a breakdown of a machine tool, in particular a hand-held machine tool, with an oscillating output movement, in particular a linearly oscillating output movement, at least one physical characteristic of the machine tool, in particular of a motor, a powertrain component, and/or a machining tool of the machine tool, is detected continuously or periodically by means of a detection unit. The method further includes detecting a deflection or a breakdown of the machine tool with an analysis unit on the basis of at least two values, which are identified at different times, of the characteristic of the machine tool, wherein each of the at least two values of the characteristic are associated with at least one respective substantially identical value of a discrete position characteristic of the oscillating output movement, in particular the linearly oscillating output movement, of the machine tool.

A method detects faults during a steady state of an operation of an induction motor. The method measures, in a time domain, a signal of a current powering the induction motor with a fundamental frequency and determines, in a frequency domain, a set of frequencies with non-zero amplitudes, such that a reconstructed signal formed by the set of frequencies with non-zero amplitudes approximates the signal measured in the time domain. The determining includes a compressive sensing via searching within a subband including the fundamental frequency of the signal subject to condition of a sparsity of the signal in the frequency domain. The method detects a fault in the induction motor if the set of frequencies includes a fault frequency different from the fundamental frequency.

A method and apparatus for protecting a circuit are provided. The method and apparatus may measure a physical quantity of a motor by an external physical stimulus, may calculate a counter electromotive voltage generated by the motor, based on the physical quantity, may compare the counter electromotive voltage to an output voltage, and may control a circuit connected to the motor to be open when the counter electromotive voltage is greater than the output voltage.